The influence of irrelevant location information on performance: A review of the Simon and spatial Stroop effects

The purpose of this paper is to investigate the effect of irrelevant location information on performance of visual choice-reaction tasks. We review empirical findings and theoretical explanations from two domains, those of the Simon effect and the spatial Stroop effect, in which stimulus location has been shown to affect reaction time when irrelevant to the task. We then integrate the findings and explanations from the two domains to clarify how and why stimulus location influences performance even when it is uninformative to the correct response. Factors that influence the processing of irrelevant location information include response modality, relative timing with respect to the relevant information, spatial coding, and allocation of attention. The most promising accounts are offered by models in which response selection is a function of (1) strength of association of the irrelevant stimulus information with the response and (2) temporal overlap of the resulting response activation with that produced by the relevant stimulus information.     

S-R compatibility effects due to context-dependent spatial stimulus coding

Responses are faster with spatial S-R correspondence than with noncorrespondence (spatial compatibility effect), even if stimulus location is irrelevant (Simon effect). In two experiments, we sought to determine whether stimuli located above and below a fixation point are coded as left and right (and thus affect the selection of left and right responses) if the visual context suggests such a coding. So, stimuli appeared on the left or right eye of a face’s image that was tilted by 90° to one side or the other (Experiment 1) or varied between upright and 45° or 90° tilting (Experiment 2). Whether stimulus location was relevant (Experiment 1) or not (Experiment 2), responses were faster with correspondence of (face-based) stimulus location and (egocentrically defined) response location, even if stimulus and response locations varied on physically orthogonal dimensions. This suggests that object-based spatial stimulus codes are formed automatically and thus influence the speed of response selection.     

Automatic spatial coding of perceived gaze direction is revealed by the Simon effect

In a typical Simon task, the (irrelevant) spatial position of the stimulus interferes with the processing of the salient characteristic (e.g., color). We used the Simon effect to investigate the automatic processing of gaze cues. We show that a simple drawing of schematic eyes automatically generates a spatially defined code of gaze direction. Although completely irrelevant to the task, direction of gaze influenced reaction times in a spatially selective two-choice discrimination based on eye color. Moreover, in one experiment employing an orthogonal manipulation of stimulus position and gaze direction, we found that coding of gaze direction is independent of stimulus spatial coding. Our finding of a “gazedirection Simon effect” is congruent with the hypothesis that gaze direction is coded by a specialized mechanism.     

Reduction of the flash-lag effect in terms of active observation

In the present study, we investigated how observers’ control of stimulus change affects temporal and spatial aspects of visual perception. We compared the illusory flash-lag effects for automatic movement of the stimulus with stimulus movement that was controlled by the observers’ active manipulation of a computer mouse (Experiments 1, 2, and 5), a keyboard (Experiment 3), or a trackball (Experiment 4). We found that the flash-lag effect was significantly reduced when the observer was familiar with the directional relationship between the mouse movement and stimulus movement on a front parallel display (Experiments 1 and 2) and that, although the unfamiliar directional relationship between the mouse movement and stimulus movement increased the flash-lag effect at the beginning of the experimental session, the repetitive observation with the same unfamiliar directional relationship reduced the flash-lag effect (Experiment 5). We found no consistent reduction of the flash-lag effect with the use of a keyboard or a trackball (Experiments 3 and 4). These results suggest that the learning of a specific directional relationship between a proprioceptive signal of hand movements and a visual signal of stimulus movements is necessary for the reduction of the flash-lag effect.     

Memory for two types of spatial location: effects of instructions, age, and format

Three experiments, with old persons (59-80 years) and college students (17-30 years) in Experiments 1 and 2 and with college students (17-24 years) in Experiment 3, investigated the differences between two types of spatial location memory: memory for the location of individual items in an array and memory for occupied, as opposed to unoccupied, locations in an array. Young persons performed better than old persons on both measures of location memory. However, an effect of instructions (intentional vs. incidental for spatial location) was consistently obtained for memory for occupied, as opposed to unoccupied, locations, whereas no effect of instructions was obtained for memory for individual item locations. In addition, item location memory was superior for objects as opposed to matched words (Experiment 2), whereas occupied location memory was not affected by presentation format (Experiments 2 and 3). These differences indicate that spatial memory is a complex process whose properties are affected by variations in stimulus characteristics and task demands. It was concluded that the distinction of Hasher and Zacks (1979) between automatic and effortful processes is not adequate for understanding spatial memory. A recognition of the complex nature of spatial processing suggests a resolution of discrepancies in the literature based upon differences in stimulus characteristics, task demands, and the effectiveness of task-appropriate mnemonic strategies.     

Effects of face and inanimate-object contexts on stimulus–response compatibility

Prior studies have shown that a left–right spatial compatibility effect occurs for vertically oriented stimuli relative to a background context of a face rotated 90° clockwise or counterclockwise from upright. For stimuli presented at the location of the eyes, the mapping of the right eye to a right response and the left eye to a left response, as would be viewed by the participant, yields better performance than does the opposite mapping. An issue of current interest in social cognition is whether animate objects are processed differently from inanimate ones. We investigated this issue in two experiments in which we compared the compatibility effects obtained with inanimate objects to those obtained with animate, face stimuli. The results showed left–right compatibility effects from the participant’s perspective for vehicles and faces from frontal and profile views, as well as for a road sign. Our findings indicate that coding of stimulus location relative to an external frame of reference is not restricted to face backgrounds.     

Top-down and bottom-up attentional control: On the nature of interference from a salient distractor

In two experiments using spatial probes, we measured the temporal and spatial interactions between top-down control of attention and bottom-up interference from a salient distractor in visual search. The subjects searched for a square among circles, ignoring color. Probe response times showed that a color singleton distractor could draw attention to its location in the early stage of visual processing (before a 100-msec stimulus onset asynchrony [SOA]), but only when the color singleton distractor was located far from the target. Apparently the bottom-up activation of the singleton distractor’s location is affected early on by local interactions with nearby stimulus locations. Moreover, probe results showed that a singleton distractor did not receive attention after extended practice. These results suggest that top-down control of attention is possible at an early stage of visual processing. In the long-SOA condition (150-msec SOA), spatial attention selected the target location over distractor locations, and this tendency occurred with or without extended practice.     

基于客体的空间一致性效应:功能可见性或空间位置编码?

采用空间Simon任务范式,考察基于客体空间一致性效应到底是手柄的功能可见性引起,还是其空间位置编码导致。实验1采用Pellicano等(2010)研究中的带手柄电筒,要求被试完成与抓握功能相关的形状判断任务,结果表明,唯有当电筒开时,被试产生了基于客体的空间一致性效应。实验2去除电筒可抓握的手柄,发现无论电筒开或关,均出现了更大的基于客体空间一致性效应。上述结果与空间编码假说一致,表明空间位置编码是产生基于客体空间一致性效应的原因。     

Object-based correspondence effects for action-relevant and surface-property judgments with keypress responses: evidence for a basis in spatial coding

It has been proposed that grasping affordances produce a Simon-type correspondence effect for left–right keypress responses and the location of the graspable part of an object for judgments based on action-relevant properties such as shape, but not on surface properties. We tested the implications of this grasping affordance account and contrasted them with the ones derived from a spatial coding account that distinguishes holistic processing of integral dimensions and analytic processing of separable dimensions. In Experiments 1–3, judgments about the color of a door handle showed a Simon effect relative to the handle’s base, whereas judgments about the handle’s shape showed no Simon effect. In Experiment 4, when the middle of the handle was colored, the Simon effect was obtained relative to the base, but when the color was at the tip of the handle or near the base, Simon effects were obtained relative to the color location. For Experiment 5, only the base was colored, and the Simon effect was larger for a passive rather than active handle state, as in the color-judgment conditions of Experiments 2–4 in which the colored region overlapped with the base. In Experiment 6, orientation judgments showed no Simon effect, as the shape judgments did in Experiments 1 and 2. The findings of (a) an absence of Simon effects for shape and orientation judgments, (b) no larger Simon effects for active than passive handle states, and (c) isolation of the changing component for color judgments are consistent with the spatial coding account, according to which the distinction between object shape/orientation and color is one of integral versus separable dimensions.     

Spontaneous decay of response-code activation

Summary Two experiments investigated whether theTwo experiments investigated whether the Simon effect (i. e.., faster responses to spatially corresponding than to noncorresponding stimuli, with stimulus location being irrelevant) is affected by the frequency of noncorrespondence trials. Stimulus discriminability (Experiment 1) and immediate or delayed stimulus formation (Experiment 2) was varied in order to manipulate the temporal relationship between coding of the relevant stimulus information and of stimulus location. As was expected, the Simon effect decreased from high to low discriminability and from immediate- to delayed-stimulus formation. This is consistent with the notion of a gradual decay of location-induced response-code activation. Moreover, the Simon effect decreased with increasing frequency of noncorrespondence trials and was even reversed with higher frequency. This demonstrates strategic preparation of stimulus processing and/or response selection based on irrelevant location information. However, frequency did not modify the interaction between S-R correspondence and stimulus discriminability or stimulus formation, this suggesting that code decay is not a result of a strategy, but an automatic process.     

Task-irrelevant distractors in the delay period interfere selectively with visual short-term memory for spatial locations

Visual short-term memory (VSTM) enables the representation of information in a readily accessible state. VSTM is typically conceptualized as a form of “active” storage that is resistant to interference or disruption, yet several recent studies have shown that under some circumstances task-irrelevant distractors may indeed disrupt performance. Here, we investigated how task-irrelevant visual distractors affected VSTM by asking whether distractors induce a general loss of remembered information or selectively interfere with memory representations. In a VSTM task, participants recalled the spatial location of a target visual stimulus after a delay in which distractors were presented on 75% of trials. Notably, the distractor’s eccentricity always matched the eccentricity of the target, while in the critical conditions the distractor’s angular position was shifted either clockwise or counterclockwise relative to the target. We then computed estimates of recall error for both eccentricity and polar angle. A general interference model would predict an effect of distractors on both polar angle and eccentricity errors, while a selective interference model would predict effects of distractors on angle but not on eccentricity errors. Results showed that for stimulus angle there was an increase in the magnitude and variability of recall errors. However, distractors had no effect on estimates of stimulus eccentricity. Our results suggest that distractors selectively interfere with VSTM for spatial locations.     

Automatic attentional orienting to other people’s gaze in schizophrenia

Explicit tests of social cognition have revealed pervasive deficits in schizophrenia. Less is known of automatic social cognition in schizophrenia. We used a spatial orienting task to investigate automatic shifts of attention cued by another person’s eye gaze in 29 patients and 28 controls. Central photographic images of a face with eyes shifted left or right, or looking straight ahead, preceded targets that appeared left or right of the cue. To examine automatic effects, cue direction was non-predictive of target location. Cue–target intervals were 100, 300, and 800?ms. In non-social control trials, arrows replaced eye-gaze cues. Both groups showed automatic attentional orienting indexed by faster reaction times (RTs) when arrows were congruent with target location across all cue–target intervals. Similar congruency effects were seen for eye-shift cues at 300 and 800?ms intervals, but patients showed significantly larger congruency effects at 800?ms, which were driven by delayed responses to incongruent target locations. At short 100-ms cue–target intervals, neither group showed faster RTs for congruent than for incongruent eye-shift cues, but patients were significantly slower to detect targets after direct-gaze cues. These findings conflict with previous studies using schematic line drawings of eye-shifts that have found automatic attentional orienting to be reduced in schizophrenia. Instead, our data indicate that patients display abnormalities in responding to gaze direction at various stages of gaze processing—reflected by a stronger preferential capture of attention by another person’s direct eye contact at initial stages of gaze processing and difficulties disengaging from a gazed-at location once shared attention is established.     

Confusion of space and time in the flash-lag effect

The apparent lagging of a short flash in the relation to a moving object, the flash-lag effect (FLE), has so far been measured mainly in terms of illusory spatial offset. We propose a method of measuring the perceived temporal asynchrony of the FLE separately from its perceived spatial offset. We presented a moving stimulus that changed its colour at a certain moment. The observer indicated, in two different tasks, where and when the colour change occurred in relation to a stationary reference flash. Results show that the perceived time of the colour change was not congruent with the perceived location of the colour change: the colour change is perceived simultaneously with the flash, but is shifted in position. The presentation of the reference in the form of a flash is not critical for the occurrence of the FLE, because the same effect was obtained with a constantly visible reference signal, the position of which or time when it changed its colour were varied. The observer was not able to ignore the irrelevant dimension of the reference signal: the apparent time of the colour change was influenced by the position of the reference signal, and the apparent location of the colour change was influenced by the presentation time of the reference signal. The observer's inability to separate the spatial and temporal aspects of the moving stimulus clearly imposes certain limits on theories that are attempting to explain the FLE exclusively in terms of the perceived space and time.     

Agency attribution and visuospatial perspective taking

We tested whether processes that evoke agency interpretations and mental state attributions also lead to adoption of the actor’s visuospatial perspective by the observer. Agency and mental state interpretations were manipulated by showing different film clips involving two triangles (the Frith-Happé animations). Participants made speeded spatial decisions while watching these films. The responses in the spatial task could be either the same or different when given from the perspective of the participant versus the perspective of one of the triangles. Reaction times were longer when the perspectives of the participants and triangles differed than when they were the same. This effect increased as the need to invoke agency interpretations in order to understand the films increased, and it increased for those films that had previously been shown to evoke mental state attributions. This demonstrates that processing of an agent’s behavior co-occurs with perspective adoption, even in the case in which triangles are the actors.     

Detection of noisy visual targets: Models for the effects of spatial uncertainty and signal-to-noise ratio

Brigham and Women’s Hospital, Boston, Massachusetts 02115 An “extreme-detector” model for detecting spatially uncertain targets in noisy backgrounds predicts how both detection and localization abilities are degraded by increasing the number of possible target locations. Experiments 1 and 2 show that the model accurately predicts detection and localization performance in tasks with two, four, and eight locations from d’ estimates of the observer’s ability to detect the target in a known spatial location. These predictions can be linked to the physical stimuli by combining the extreme-detector model with a “psychophysical” model that specifies how stimulus measures determine the target’s detectability in a given location. Single-parameter fits of four such combined models were compared with estimates of detection and localization performance in Experiment 3, which manipulated the target’s physical signal-to-noise ratio across various conditions of an eightlocation task.     

Effects of Expectancy and Attention in Vibrotactile Choice Reaction Time Tasks

The orienting of attention in space has not been considered in the tactile domain. This issue is examined using a modified version of a visual paradigm initially adopted by Posner, Snyder, and Davidson (1980), which manipulates the probability of a stimulus occurring at different spatial locations. Slower RTs at an unexpected stimulus location are thought to reflect the time required to shift attention from the expected to the unexpected location. In two experiments involving vibrotactile choice RT between left and right hands, the two hands were either crossed or uncrossed, and the hands were held both on the left side of the body, both on the right, or one on either side of the midline. There was no evidence to suggest that spatial location (left or right) affected the orienting of attention in the tactual modality. As predicted, RTs were slower when the arms were crossed compared with uncrossed, though this effect was smaller for the expected trials. A coding conflict hypothesis may explain both these findings, but the smaller effect in the expected trials may also reflect attentional factors. Both the relative and absolute location of the hands affected the magnitude of the crossed-arm effect and indicated that attention may play a role in the perceptual division of space into left and right sides. Possible reasons for hand or hemispace asymmetries in different simple and choice RT paradigms were discussed.     

Practice-induced and sequential modulations of the Simon effect

People react more quickly and more accurately to stimuli presented in locations corresponding to the response, as compared with noncorresponding locations, even when stimulus location is irrelevant (Simon effect [SE]). The explanation that SEs are caused by the automatic priming of a corresponding response has been questioned, because of the many exceptions to the effect. We replicated practice-induced and sequential modulations of the SE in two experiments—first, by training participants with blocks of location-relevant stimuli, and second, by mixing location-relevant and location-irrelevant trials. The decrease of the SE with incompatible training was relatively permanent in the blocked experiment, whereas the effect was temporary in the mixed experiment. The difference was caused by a more permanent reversal of the SE after incongruent trials, showing that sequential modulations depend on long-term practice effects. We suggest that there is a formation of a contralateral longterm memory stimulus-response link in blocked conditions and that short-term and long-term memory links are primed by preceding events.     

Spatial location judgments as a function of intention to learn, and mood state: an evaluation of an alleged automatic encoding operation

An assessment of the Hasher and Zacks (1979) conceptualization of the automatic nature of the acquisition of spatial location information was made in the context of manipulations of subjects' intention to learn and mood state. The Velten (1968) mood induction procedure was used to establish depressed and nondepressed subjects. Half of each group was then presented with a matrix of geometric forms under instructions to learn the location of the forms (intentional) or to evaluate the pleasantness of the array (incidental). Subsequent tests of spatial location performance found no differences as a function of subjects' mood state, but did find a strong effect for instructional condition. The superior performance of the intentional subjects raises questions about the automatic nature of the encoding of spatial location.     

Parafoveal letter-position coding in reading

The masked-priming lexical decision task has been the paradigm of choice for investigating how readers code for letter identity and position. Insight into the temporal integration of information between prime and target words has pointed out, among other things, that readers do not code for the absolute position of letters. This conception has spurred various accounts of the word recognition process, but the results at present do not favor one account in particular. Thus, employing a new strategy, the present study moves out of the arena of temporal- and into the arena of spatial information integration. We present two lexical decision experiments that tested how the processing of six-letter target words is influenced by simultaneously presented flanking stimuli (each stimulus was presented for 150 ms). We manipulated the orthographic relatedness between the targets and flankers, in terms of both letter identity (same/different letters based on the target’s outer/inner letters) and letter position (intact/reversed order of letters and of flankers, contiguous/noncontiguous flankers). Target processing was strongly facilitated by same-letter flankers, and this facilitatory effect was modulated by both letter/flanker order and contiguity. However, when the flankers consisted of the target’s inner-positioned letters alone, letter order no longer mattered. These findings suggest that readers may code for the relative position of letters using words’ edges as spatial points of reference. We conclude that the flanker paradigm provides a fruitful means to investigate letter-position coding in the fovea and parafovea.     

Representing response position relative to display location: Influence on orthogonal stimulus-response compatibility

Two types of stimulus-response compatibility (SRC) effect occur with orthogonal stimulus and response sets, an overall up-right/down-left advantage and mapping preferences that vary with response position. Researchers agree that the former type is due to asymmetric coding of the stimulus and response alternatives, but disagree as to whether the latter type requires a different explanation in terms of the properties of the motor system. This issue is examined in three experiments. The location of the stimulus set influenced orthogonal SRC when it varied along the same dimension as the responses (Experiments 1 and 2), with the pattern predicted by the hypothesis that the stimulus set provides a referent relative to which response position is coded. The effect of stimulus-set location on orthogonal SRC was independent of the stimulus onset asynchrony (SOA) for a marker that indicated stimulus-set side and the imperative stimulus. In contrast, a spatial correspondence effect for the irrelevant stimulus-set location and response was a decreasing function of SOA. Experiment 3 showed that the orthogonal SRC effect was determined by response position relative to the stimulus-set location and not the body midline. The results support the view that both types of orthogonal SRC effects are due to asymmetric coding of the stimuli and responses.